1 files changed, 37 insertions, 15 deletions

diff --git a/drivers/hid/hid-multitouch.c b/drivers/hid/hid-multitouch.c
index ee01e65e22d6..b9f9eeceaa98 100644
--- a/drivers/hid/hid-multitouch.c
+++ b/drivers/hid/hid-multitouch.c
@@ -60,8 +60,9 @@ struct mt_device {
         __s8 inputmode;         /* InputMode HID feature, -1 if non-existent */
         __u8 num_received;      /* how many contacts we received */
         __u8 num_expected;      /* expected last contact index */
+        __u8 maxcontacts;
         bool curvalid;          /* is the current contact valid? */
-        struct mt_slot slots[0];        /* first slot */
+        struct mt_slot *slots;
 };
 
 struct mt_class {
@@ -79,6 +80,8 @@ struct mt_class {
 #define MT_CLS_CYPRESS                          4
 #define MT_CLS_EGALAX                           5
 
+#define MT_DEFAULT_MAXCONTACT   10
+
 /*
  * these device-dependent functions determine what slot corresponds
  * to a valid contact that was just read.
@@ -95,12 +98,12 @@ static int cypress_compute_slot(struct mt_device *td)
 static int find_slot_from_contactid(struct mt_device *td)
 {
         int i;
-        for (i = 0; i < td->mtclass->maxcontacts; ++i) {
+        for (i = 0; i < td->maxcontacts; ++i) {
                 if (td->slots[i].contactid == td->curdata.contactid &&
                         td->slots[i].touch_state)
                         return i;
         }
-        for (i = 0; i < td->mtclass->maxcontacts; ++i) {
+        for (i = 0; i < td->maxcontacts; ++i) {
                 if (!td->slots[i].seen_in_this_frame &&
                         !td->slots[i].touch_state)
                         return i;
@@ -113,8 +116,7 @@ static int find_slot_from_contactid(struct mt_device *td)
 
 struct mt_class mt_classes[] = {
         { .name = MT_CLS_DEFAULT,
-                .quirks = MT_QUIRK_NOT_SEEN_MEANS_UP,
-                .maxcontacts = 10 },
+                .quirks = MT_QUIRK_NOT_SEEN_MEANS_UP },
         { .name = MT_CLS_DUAL_INRANGE_CONTACTID,
                 .quirks = MT_QUIRK_VALID_IS_INRANGE |
                         MT_QUIRK_SLOT_IS_CONTACTID,
@@ -142,9 +144,19 @@ struct mt_class mt_classes[] = {
 static void mt_feature_mapping(struct hid_device *hdev,
                 struct hid_field *field, struct hid_usage *usage)
 {
-        if (usage->hid == HID_DG_INPUTMODE) {
-                struct mt_device *td = hid_get_drvdata(hdev);
+        struct mt_device *td = hid_get_drvdata(hdev);
+
+        switch (usage->hid) {
+        case HID_DG_INPUTMODE:
                 td->inputmode = field->report->id;
+                break;
+        case HID_DG_CONTACTMAX:
+                td->maxcontacts = field->value[0];
+                if (td->mtclass->maxcontacts)
+                        /* check if the maxcontacts is given by the class */
+                        td->maxcontacts = td->mtclass->maxcontacts;
+
+                break;
         }
 }
 
@@ -208,8 +220,7 @@ static int mt_input_mapping(struct hid_device *hdev, struct hid_input *hi,
                         td->last_slot_field = usage->hid;
                         return 1;
                 case HID_DG_CONTACTID:
-                        input_mt_init_slots(hi->input,
-                                        td->mtclass->maxcontacts);
+                        input_mt_init_slots(hi->input, td->maxcontacts);
                         td->last_slot_field = usage->hid;
                         return 1;
                 case HID_DG_WIDTH:
@@ -292,7 +303,7 @@ static void mt_complete_slot(struct mt_device *td)
         if (td->curvalid) {
                 int slotnum = mt_compute_slot(td);
 
-                if (slotnum >= 0 && slotnum < td->mtclass->maxcontacts)
+                if (slotnum >= 0 && slotnum < td->maxcontacts)
                         td->slots[slotnum] = td->curdata;
         }
         td->num_received++;
@@ -307,7 +318,7 @@ static void mt_emit_event(struct mt_device *td, struct input_dev *input)
 {
         int i;
 
-        for (i = 0; i < td->mtclass->maxcontacts; ++i) {
+        for (i = 0; i < td->maxcontacts; ++i) {
                 struct mt_slot *s = &(td->slots[i]);
                 if ((td->mtclass->quirks & MT_QUIRK_NOT_SEEN_MEANS_UP) &&
                         !s->seen_in_this_frame) {
@@ -341,7 +352,7 @@ static int mt_event(struct hid_device *hid, struct hid_field *field,
         struct mt_device *td = hid_get_drvdata(hid);
         __s32 quirks = td->mtclass->quirks;
 
-        if (hid->claimed & HID_CLAIMED_INPUT) {
+        if (hid->claimed & HID_CLAIMED_INPUT && td->slots) {
                 switch (usage->hid) {
                 case HID_DG_INRANGE:
                         if (quirks & MT_QUIRK_VALID_IS_INRANGE)
@@ -442,9 +453,7 @@ static int mt_probe(struct hid_device *hdev, const struct hid_device_id *id)
          */
         hdev->quirks |= HID_QUIRK_NO_INPUT_SYNC;
 
-        td = kzalloc(sizeof(struct mt_device) +
-                                mtclass->maxcontacts * sizeof(struct mt_slot),
-                                GFP_KERNEL);
+        td = kzalloc(sizeof(struct mt_device), GFP_KERNEL);
         if (!td) {
                 dev_err(&hdev->dev, "cannot allocate multitouch data\n");
                 return -ENOMEM;
@@ -461,6 +470,18 @@ static int mt_probe(struct hid_device *hdev, const struct hid_device_id *id)
         if (ret)
                 goto fail;
 
+        if (!td->maxcontacts)
+                td->maxcontacts = MT_DEFAULT_MAXCONTACT;
+
+        td->slots = kzalloc(td->maxcontacts * sizeof(struct mt_slot),
+                                GFP_KERNEL);
+        if (!td->slots) {
+                dev_err(&hdev->dev, "cannot allocate multitouch slots\n");
+                hid_hw_stop(hdev);
+                ret = -ENOMEM;
+                goto fail;
+        }
+
         mt_set_input_mode(hdev);
 
         return 0;
@@ -482,6 +503,7 @@ static void mt_remove(struct hid_device *hdev)
 {
         struct mt_device *td = hid_get_drvdata(hdev);
         hid_hw_stop(hdev);
+        kfree(td->slots);
         kfree(td);
         hid_set_drvdata(hdev, NULL);
 }